Preservation of food by dehydration is well known in the art. The early dehydration of food was typically carried out by placing the food product in an open container exposed to the air and to the sun. In more recent times, mechanical food dehydrators have been developed for use in the home, as well as for use in industry. Examples of such devices are described in U.S. Pat. Nos. 1,954,239, 2,017,728, 2,412,407 and 4,190,965, and are incorporated herein by reference. The known food dehydrators often include a plurality of shelves contained within a cabinet onto which the food to be dried is placed. The dehydrator typically uses a motor-driven fan to draw air in through openings and circulate the air throughout the dehydrator. A heater is provided for heating the air before it is circulated by the fan throughout the dehydrator.
One issue common to known food dehydrators is their need to regulate the temperature within the dehydrator at a uniform and safe operating level. This need is especially urgent since most motors typically used in dehydrators are often inefficient. One example of such a motor is the shaded pole motor, which runs at only 40-50% efficiency. As a result, they can become quite hot during use. While the venting and cooling systems provided within the dehydrators help to cool the motors, the risk of overheating is not eliminated.
Excess temperatures, however, can overheat the dehydrator and cause damage to its internal components. Overheating also poses serious safety hazards to persons using the dehydrator. It has been typical, therefore, to insert temperature-regulating devices, such as thermostats within the dehydrator to minimize the risk of overheating. The addition of thermostate, however, increases the overall cost of the dehydrator in several respects. To being with, the thermostats themselves are an element of cost. Moreover, additional structure must be added to the dehydrator in order to support the thermostat within the dehydrator. As a result, not only the material cost, but also the labor costs involved in manufacturing and assembling the dehydrator are increased. On the other hand, the applicant has determined that there is a demand for a food dehydrator which is relatively inexpensive to manufacture.
Accordingly, there is a need for a food dehydrator which provides for regulation of the temperature within the dehydrator without the need for additional temperature-regulating devices, such as a thermostat, so that a food dehydrator that is relatively inexpensive to manufacture and assembly may be achieved.